Ron,
It completely depends on the size of the marketing team and your firm.
When I first deployed Marketo, I was the global admin and regional marketer and then cross-trained everyone on using the system, but no one else had admin powers. You need to make sure only a highly trained marketer or SFDC Admin has that level of access. They need to understand how Marketo+SFDC work and how they work apart. Admins should be comfortable being the tech support for marketo before you call Marketo.
Larger teams or firms with larger systems issues will need someone who is a CRM/Marketo Admin who knows how to handle API/jquery. Some teams I've seen have SFDC Admins, Marketing Admins, and a Web Guru/HTML guy and then marketers who run various programs.
I found the training hours Marketo offered to be a bit helpful for the non admins. I did not try to "accomplish" anything during those sessions because I had already defined what needed to happen. I'd use them to help train the rest of the team.
As I discuss in the
Marketing Rockstar's Guide to Marketo, any system should have clear rules around Naming and Organization and any upload procedures.